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A t with subscript one-half, the time for half a quantity to decay.
Also known as: Half life, t with a half underneath
t½ is the time for half of a decaying quantity to remain. It is constant regardless of how much you start with, which is the surprising property that makes radiometric dating possible.
Relates to the decay constant by a fixed factor, so a source stating one implicitly states the other.
Contexts: Mathematics, Laboratory
Is independent of the starting amount, which is what makes it a property of the substance rather than of the sample — and what makes radiometric dating possible.
Contexts: Mathematics, Laboratory
Denotes the time required for half of a decaying quantity to remain, whether of radioactive nuclei or of a drug in the body.
Contexts: Mathematics, Laboratory
A lower-case italic letter t followed by a subscript fraction one-half, its numeral and divider set below the baseline.
Activity and half-life are the two ways a source's decay is described.